Number of form for Permanent Residency

I am in possession of a subclass 475 Visa and I now want to apply for Permanent Residence. What is the number of the form that I should fill in. I believe one can apply for a subclass 887 or 857 Permanent Resident Visa but am led to believe that the 857 one is better as I have Regional Sponsorship.

Please let me know what you think and PLEASE TELL ME THE NUMBER OF THE FORM THAT I NEED TO COMPLETE. The DIAC site has a huge list of forms but if you don't know the number of the form, it is impossible to find.

Thanks so much !

Seaton McTavish